# Tikz drawing with function

I wanna know a clear way to code the function while drawing with it, for ex. how to write this f(x)= -(x+1)(x-2)(x-4)

how to code it in the below command?

\draw [red,ultra thick,domain=-1:2,samples=400,latex-latex] plot (\x,---);


Please there is any clear coding way for these cases?

i tried but it in -5(x + 3)(x-1)(x-2)(x-7) but it didn't work

please wanna coding way for the functions like sin(x) or tan(x)

• Please have a look at the pgfplots package. I guess that you are a total beginner. In that case, I recommend reading an introduction to LaTex first (I recommend a recent book). – Dr. Manuel Kuehner Dec 5 '17 at 9:39
• @MarwaHashem is your question solved? Would you accept an answer? – Bobyandbob Sep 24 '18 at 9:11

## 2 Answers

\documentclass[a4paper]{article}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}
\draw[very thin,color=black] (-0,-0) grid (4,4);

\draw[->] (-0.2,0) -- (4.2,0) node[right] {$x$};
\draw[->] (0,-1.2) -- (0,4.2) node[above] {$f(x)$};

\draw[blue] (0,0) plot[domain=2:4] (\x,{-(\x+1)*(\x-2)*(\x-4)}) node[anchor=south west] {$V_{p}$};

\end{tikzpicture}
\end{document}


• i tried but it in -5(x + 3)(x-1)(x-2)(x-7) but it didn't work – Marwa Hashem Dec 5 '17 at 8:30
• @MarwaHashem You need to have * between them to express multiplication, i.e. -5*(x+3)*(x-1)*(x-2)*(x-7). – user156344 Apr 1 '19 at 10:44

A simple way using pgfplots for your function -5(x + 3)(x-1)(x-2)(x-7):

\documentclass[border=10pt]{standalone}
\usepackage{pgfplots}
\pgfplotsset{width=7cm,compat=1.8}
\begin{document}
\begin{tikzpicture}
\begin{axis}[
domain     = -5:8,
ymin       = -2000,
ymax       =  2000,
samples    = 50,
axis lines = middle
]
\addplot [mark = none, color = blue]
{-5*(x + 3)*(x-1)*(x-2)*(x-7)};
\end{axis}
\end{tikzpicture}
\end{document}